Sierra re-introduces repairing permissions Permissions repair tools updated for compatibility with High Sierra Should you repair permissions on your Home folder, and how?
When an app or its installer won’t run after download Solving update problems with softwareupdate What to do when a disk image won’t mount Disk Utility: An ever-changing tool Was that a crash, freeze, panic, or spinning beachball?
A list of articles to help you solve problems on Macs running El Capitan or Sierra (10.11 and 10.12).
For older articles about previous versions of OS X, see this article. mac OS 10.13.4 update may help Do you use PGP/GPG and S/MIME email encryption?
Forensic analysis for APFS volumes Customising it all: global defaults in mac OS Sierra and High Sierra mac OS 10.14 Is Apple about to drop Quick Time, DVD and i Work support, and Compressor?
How it doesn’t work like it used to When should you re-install mac OS?A diagnostic guide Kernel panics, and how to know when they occur Why the spinning beachball?Firmware, the SMC, and NVRAM: reset and maintain Startup tones, EFI, and fixing failed firmware updates Which EFI firmware should your Mac be using?Mac shutdown and sleep cause codes Sleep, Wake, and Startup: Hardware and ACPI Self-starting Macs, startup chimes, and other secrets of NVRAM Which EFI firmware should your Mac be using?Restoring order to EFI firmware There’s trouble in that firmware: EFI chaos Just what do XProtect and MRT protect your Mac from?